linux/drivers/rtc/rtc-ab8500.c
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   1/*
   2 * Copyright (C) ST-Ericsson SA 2010
   3 *
   4 * License terms: GNU General Public License (GPL) version 2
   5 * Author: Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>
   6 *
   7 * RTC clock driver for the RTC part of the AB8500 Power management chip.
   8 * Based on RTC clock driver for the AB3100 Analog Baseband Chip by
   9 * Linus Walleij <linus.walleij@stericsson.com>
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/kernel.h>
  14#include <linux/init.h>
  15#include <linux/platform_device.h>
  16#include <linux/rtc.h>
  17#include <linux/mfd/abx500.h>
  18#include <linux/mfd/abx500/ab8500.h>
  19#include <linux/delay.h>
  20#include <linux/of.h>
  21
  22#define AB8500_RTC_SOFF_STAT_REG        0x00
  23#define AB8500_RTC_CC_CONF_REG          0x01
  24#define AB8500_RTC_READ_REQ_REG         0x02
  25#define AB8500_RTC_WATCH_TSECMID_REG    0x03
  26#define AB8500_RTC_WATCH_TSECHI_REG     0x04
  27#define AB8500_RTC_WATCH_TMIN_LOW_REG   0x05
  28#define AB8500_RTC_WATCH_TMIN_MID_REG   0x06
  29#define AB8500_RTC_WATCH_TMIN_HI_REG    0x07
  30#define AB8500_RTC_ALRM_MIN_LOW_REG     0x08
  31#define AB8500_RTC_ALRM_MIN_MID_REG     0x09
  32#define AB8500_RTC_ALRM_MIN_HI_REG      0x0A
  33#define AB8500_RTC_STAT_REG             0x0B
  34#define AB8500_RTC_BKUP_CHG_REG         0x0C
  35#define AB8500_RTC_FORCE_BKUP_REG       0x0D
  36#define AB8500_RTC_CALIB_REG            0x0E
  37#define AB8500_RTC_SWITCH_STAT_REG      0x0F
  38#define AB8540_RTC_ALRM_SEC             0x22
  39#define AB8540_RTC_ALRM_MIN_LOW_REG     0x23
  40#define AB8540_RTC_ALRM_MIN_MID_REG     0x24
  41#define AB8540_RTC_ALRM_MIN_HI_REG      0x25
  42
  43/* RtcReadRequest bits */
  44#define RTC_READ_REQUEST                0x01
  45#define RTC_WRITE_REQUEST               0x02
  46
  47/* RtcCtrl bits */
  48#define RTC_ALARM_ENA                   0x04
  49#define RTC_STATUS_DATA                 0x01
  50
  51#define COUNTS_PER_SEC                  (0xF000 / 60)
  52#define AB8500_RTC_EPOCH                2000
  53
  54static const u8 ab8500_rtc_time_regs[] = {
  55        AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
  56        AB8500_RTC_WATCH_TMIN_LOW_REG, AB8500_RTC_WATCH_TSECHI_REG,
  57        AB8500_RTC_WATCH_TSECMID_REG
  58};
  59
  60static const u8 ab8500_rtc_alarm_regs[] = {
  61        AB8500_RTC_ALRM_MIN_HI_REG, AB8500_RTC_ALRM_MIN_MID_REG,
  62        AB8500_RTC_ALRM_MIN_LOW_REG
  63};
  64
  65static const u8 ab8540_rtc_alarm_regs[] = {
  66        AB8540_RTC_ALRM_MIN_HI_REG, AB8540_RTC_ALRM_MIN_MID_REG,
  67        AB8540_RTC_ALRM_MIN_LOW_REG, AB8540_RTC_ALRM_SEC
  68};
  69
  70/* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
  71static unsigned long get_elapsed_seconds(int year)
  72{
  73        unsigned long secs;
  74        struct rtc_time tm = {
  75                .tm_year = year - 1900,
  76                .tm_mday = 1,
  77        };
  78
  79        /*
  80         * This function calculates secs from 1970 and not from
  81         * 1900, even if we supply the offset from year 1900.
  82         */
  83        rtc_tm_to_time(&tm, &secs);
  84        return secs;
  85}
  86
  87static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  88{
  89        unsigned long timeout = jiffies + HZ;
  90        int retval, i;
  91        unsigned long mins, secs;
  92        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
  93        u8 value;
  94
  95        /* Request a data read */
  96        retval = abx500_set_register_interruptible(dev,
  97                AB8500_RTC, AB8500_RTC_READ_REQ_REG, RTC_READ_REQUEST);
  98        if (retval < 0)
  99                return retval;
 100
 101        /* Wait for some cycles after enabling the rtc read in ab8500 */
 102        while (time_before(jiffies, timeout)) {
 103                retval = abx500_get_register_interruptible(dev,
 104                        AB8500_RTC, AB8500_RTC_READ_REQ_REG, &value);
 105                if (retval < 0)
 106                        return retval;
 107
 108                if (!(value & RTC_READ_REQUEST))
 109                        break;
 110
 111                usleep_range(1000, 5000);
 112        }
 113
 114        /* Read the Watchtime registers */
 115        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 116                retval = abx500_get_register_interruptible(dev,
 117                        AB8500_RTC, ab8500_rtc_time_regs[i], &value);
 118                if (retval < 0)
 119                        return retval;
 120                buf[i] = value;
 121        }
 122
 123        mins = (buf[0] << 16) | (buf[1] << 8) | buf[2];
 124
 125        secs =  (buf[3] << 8) | buf[4];
 126        secs =  secs / COUNTS_PER_SEC;
 127        secs =  secs + (mins * 60);
 128
 129        /* Add back the initially subtracted number of seconds */
 130        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 131
 132        rtc_time_to_tm(secs, tm);
 133        return rtc_valid_tm(tm);
 134}
 135
 136static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
 137{
 138        int retval, i;
 139        unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
 140        unsigned long no_secs, no_mins, secs = 0;
 141
 142        if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
 143                dev_dbg(dev, "year should be equal to or greater than %d\n",
 144                                AB8500_RTC_EPOCH);
 145                return -EINVAL;
 146        }
 147
 148        /* Get the number of seconds since 1970 */
 149        rtc_tm_to_time(tm, &secs);
 150
 151        /*
 152         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 153         * we only have a small counter in the RTC.
 154         */
 155        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 156
 157        no_mins = secs / 60;
 158
 159        no_secs = secs % 60;
 160        /* Make the seconds count as per the RTC resolution */
 161        no_secs = no_secs * COUNTS_PER_SEC;
 162
 163        buf[4] = no_secs & 0xFF;
 164        buf[3] = (no_secs >> 8) & 0xFF;
 165
 166        buf[2] = no_mins & 0xFF;
 167        buf[1] = (no_mins >> 8) & 0xFF;
 168        buf[0] = (no_mins >> 16) & 0xFF;
 169
 170        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_time_regs); i++) {
 171                retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 172                        ab8500_rtc_time_regs[i], buf[i]);
 173                if (retval < 0)
 174                        return retval;
 175        }
 176
 177        /* Request a data write */
 178        return abx500_set_register_interruptible(dev, AB8500_RTC,
 179                AB8500_RTC_READ_REQ_REG, RTC_WRITE_REQUEST);
 180}
 181
 182static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 183{
 184        int retval, i;
 185        u8 rtc_ctrl, value;
 186        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 187        unsigned long secs, mins;
 188
 189        /* Check if the alarm is enabled or not */
 190        retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 191                AB8500_RTC_STAT_REG, &rtc_ctrl);
 192        if (retval < 0)
 193                return retval;
 194
 195        if (rtc_ctrl & RTC_ALARM_ENA)
 196                alarm->enabled = 1;
 197        else
 198                alarm->enabled = 0;
 199
 200        alarm->pending = 0;
 201
 202        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 203                retval = abx500_get_register_interruptible(dev, AB8500_RTC,
 204                        ab8500_rtc_alarm_regs[i], &value);
 205                if (retval < 0)
 206                        return retval;
 207                buf[i] = value;
 208        }
 209
 210        mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
 211        secs = mins * 60;
 212
 213        /* Add back the initially subtracted number of seconds */
 214        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
 215
 216        rtc_time_to_tm(secs, &alarm->time);
 217
 218        return rtc_valid_tm(&alarm->time);
 219}
 220
 221static int ab8500_rtc_irq_enable(struct device *dev, unsigned int enabled)
 222{
 223        return abx500_mask_and_set_register_interruptible(dev, AB8500_RTC,
 224                AB8500_RTC_STAT_REG, RTC_ALARM_ENA,
 225                enabled ? RTC_ALARM_ENA : 0);
 226}
 227
 228static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 229{
 230        int retval, i;
 231        unsigned char buf[ARRAY_SIZE(ab8500_rtc_alarm_regs)];
 232        unsigned long mins, secs = 0, cursec = 0;
 233        struct rtc_time curtm;
 234
 235        if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 236                dev_dbg(dev, "year should be equal to or greater than %d\n",
 237                                AB8500_RTC_EPOCH);
 238                return -EINVAL;
 239        }
 240
 241        /* Get the number of seconds since 1970 */
 242        rtc_tm_to_time(&alarm->time, &secs);
 243
 244        /*
 245         * Check whether alarm is set less than 1min.
 246         * Since our RTC doesn't support alarm resolution less than 1min,
 247         * return -EINVAL, so UIE EMUL can take it up, incase of UIE_ON
 248         */
 249        ab8500_rtc_read_time(dev, &curtm); /* Read current time */
 250        rtc_tm_to_time(&curtm, &cursec);
 251        if ((secs - cursec) < 59) {
 252                dev_dbg(dev, "Alarm less than 1 minute not supported\r\n");
 253                return -EINVAL;
 254        }
 255
 256        /*
 257         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
 258         * we only have a small counter in the RTC.
 259         */
 260        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 261
 262        mins = secs / 60;
 263
 264        buf[2] = mins & 0xFF;
 265        buf[1] = (mins >> 8) & 0xFF;
 266        buf[0] = (mins >> 16) & 0xFF;
 267
 268        /* Set the alarm time */
 269        for (i = 0; i < ARRAY_SIZE(ab8500_rtc_alarm_regs); i++) {
 270                retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 271                        ab8500_rtc_alarm_regs[i], buf[i]);
 272                if (retval < 0)
 273                        return retval;
 274        }
 275
 276        return ab8500_rtc_irq_enable(dev, alarm->enabled);
 277}
 278
 279static int ab8540_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 280{
 281        int retval, i;
 282        unsigned char buf[ARRAY_SIZE(ab8540_rtc_alarm_regs)];
 283        unsigned long mins, secs = 0;
 284
 285        if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
 286                dev_dbg(dev, "year should be equal to or greater than %d\n",
 287                                AB8500_RTC_EPOCH);
 288                return -EINVAL;
 289        }
 290
 291        /* Get the number of seconds since 1970 */
 292        rtc_tm_to_time(&alarm->time, &secs);
 293
 294        /*
 295         * Convert it to the number of seconds since 01-01-2000 00:00:00
 296         */
 297        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
 298        mins = secs / 60;
 299
 300        buf[3] = secs % 60;
 301        buf[2] = mins & 0xFF;
 302        buf[1] = (mins >> 8) & 0xFF;
 303        buf[0] = (mins >> 16) & 0xFF;
 304
 305        /* Set the alarm time */
 306        for (i = 0; i < ARRAY_SIZE(ab8540_rtc_alarm_regs); i++) {
 307                retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 308                        ab8540_rtc_alarm_regs[i], buf[i]);
 309                if (retval < 0)
 310                        return retval;
 311        }
 312
 313        return ab8500_rtc_irq_enable(dev, alarm->enabled);
 314}
 315
 316static int ab8500_rtc_set_calibration(struct device *dev, int calibration)
 317{
 318        int retval;
 319        u8  rtccal = 0;
 320
 321        /*
 322         * Check that the calibration value (which is in units of 0.5
 323         * parts-per-million) is in the AB8500's range for RtcCalibration
 324         * register. -128 (0x80) is not permitted because the AB8500 uses
 325         * a sign-bit rather than two's complement, so 0x80 is just another
 326         * representation of zero.
 327         */
 328        if ((calibration < -127) || (calibration > 127)) {
 329                dev_err(dev, "RtcCalibration value outside permitted range\n");
 330                return -EINVAL;
 331        }
 332
 333        /*
 334         * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 335         * so need to convert to this sort of representation before writing
 336         * into RtcCalibration register...
 337         */
 338        if (calibration >= 0)
 339                rtccal = 0x7F & calibration;
 340        else
 341                rtccal = ~(calibration - 1) | 0x80;
 342
 343        retval = abx500_set_register_interruptible(dev, AB8500_RTC,
 344                        AB8500_RTC_CALIB_REG, rtccal);
 345
 346        return retval;
 347}
 348
 349static int ab8500_rtc_get_calibration(struct device *dev, int *calibration)
 350{
 351        int retval;
 352        u8  rtccal = 0;
 353
 354        retval =  abx500_get_register_interruptible(dev, AB8500_RTC,
 355                        AB8500_RTC_CALIB_REG, &rtccal);
 356        if (retval >= 0) {
 357                /*
 358                 * The AB8500 uses sign (in bit7) and magnitude (in bits0-7)
 359                 * so need to convert value from RtcCalibration register into
 360                 * a two's complement signed value...
 361                 */
 362                if (rtccal & 0x80)
 363                        *calibration = 0 - (rtccal & 0x7F);
 364                else
 365                        *calibration = 0x7F & rtccal;
 366        }
 367
 368        return retval;
 369}
 370
 371static ssize_t ab8500_sysfs_store_rtc_calibration(struct device *dev,
 372                                struct device_attribute *attr,
 373                                const char *buf, size_t count)
 374{
 375        int retval;
 376        int calibration = 0;
 377
 378        if (sscanf(buf, " %i ", &calibration) != 1) {
 379                dev_err(dev, "Failed to store RTC calibration attribute\n");
 380                return -EINVAL;
 381        }
 382
 383        retval = ab8500_rtc_set_calibration(dev, calibration);
 384
 385        return retval ? retval : count;
 386}
 387
 388static ssize_t ab8500_sysfs_show_rtc_calibration(struct device *dev,
 389                                struct device_attribute *attr, char *buf)
 390{
 391        int  retval = 0;
 392        int  calibration = 0;
 393
 394        retval = ab8500_rtc_get_calibration(dev, &calibration);
 395        if (retval < 0) {
 396                dev_err(dev, "Failed to read RTC calibration attribute\n");
 397                sprintf(buf, "0\n");
 398                return retval;
 399        }
 400
 401        return sprintf(buf, "%d\n", calibration);
 402}
 403
 404static DEVICE_ATTR(rtc_calibration, S_IRUGO | S_IWUSR,
 405                   ab8500_sysfs_show_rtc_calibration,
 406                   ab8500_sysfs_store_rtc_calibration);
 407
 408static int ab8500_sysfs_rtc_register(struct device *dev)
 409{
 410        return device_create_file(dev, &dev_attr_rtc_calibration);
 411}
 412
 413static void ab8500_sysfs_rtc_unregister(struct device *dev)
 414{
 415        device_remove_file(dev, &dev_attr_rtc_calibration);
 416}
 417
 418static irqreturn_t rtc_alarm_handler(int irq, void *data)
 419{
 420        struct rtc_device *rtc = data;
 421        unsigned long events = RTC_IRQF | RTC_AF;
 422
 423        dev_dbg(&rtc->dev, "%s\n", __func__);
 424        rtc_update_irq(rtc, 1, events);
 425
 426        return IRQ_HANDLED;
 427}
 428
 429static const struct rtc_class_ops ab8500_rtc_ops = {
 430        .read_time              = ab8500_rtc_read_time,
 431        .set_time               = ab8500_rtc_set_time,
 432        .read_alarm             = ab8500_rtc_read_alarm,
 433        .set_alarm              = ab8500_rtc_set_alarm,
 434        .alarm_irq_enable       = ab8500_rtc_irq_enable,
 435};
 436
 437static const struct rtc_class_ops ab8540_rtc_ops = {
 438        .read_time              = ab8500_rtc_read_time,
 439        .set_time               = ab8500_rtc_set_time,
 440        .read_alarm             = ab8500_rtc_read_alarm,
 441        .set_alarm              = ab8540_rtc_set_alarm,
 442        .alarm_irq_enable       = ab8500_rtc_irq_enable,
 443};
 444
 445static struct platform_device_id ab85xx_rtc_ids[] = {
 446        { "ab8500-rtc", (kernel_ulong_t)&ab8500_rtc_ops, },
 447        { "ab8540-rtc", (kernel_ulong_t)&ab8540_rtc_ops, },
 448};
 449
 450static int ab8500_rtc_probe(struct platform_device *pdev)
 451{
 452        const struct platform_device_id *platid = platform_get_device_id(pdev);
 453        int err;
 454        struct rtc_device *rtc;
 455        u8 rtc_ctrl;
 456        int irq;
 457
 458        irq = platform_get_irq_byname(pdev, "ALARM");
 459        if (irq < 0)
 460                return irq;
 461
 462        /* For RTC supply test */
 463        err = abx500_mask_and_set_register_interruptible(&pdev->dev, AB8500_RTC,
 464                AB8500_RTC_STAT_REG, RTC_STATUS_DATA, RTC_STATUS_DATA);
 465        if (err < 0)
 466                return err;
 467
 468        /* Wait for reset by the PorRtc */
 469        usleep_range(1000, 5000);
 470
 471        err = abx500_get_register_interruptible(&pdev->dev, AB8500_RTC,
 472                AB8500_RTC_STAT_REG, &rtc_ctrl);
 473        if (err < 0)
 474                return err;
 475
 476        /* Check if the RTC Supply fails */
 477        if (!(rtc_ctrl & RTC_STATUS_DATA)) {
 478                dev_err(&pdev->dev, "RTC supply failure\n");
 479                return -ENODEV;
 480        }
 481
 482        device_init_wakeup(&pdev->dev, true);
 483
 484        rtc = devm_rtc_device_register(&pdev->dev, "ab8500-rtc",
 485                                (struct rtc_class_ops *)platid->driver_data,
 486                                THIS_MODULE);
 487        if (IS_ERR(rtc)) {
 488                dev_err(&pdev->dev, "Registration failed\n");
 489                err = PTR_ERR(rtc);
 490                return err;
 491        }
 492
 493        err = devm_request_threaded_irq(&pdev->dev, irq, NULL,
 494                        rtc_alarm_handler, IRQF_NO_SUSPEND | IRQF_ONESHOT,
 495                        "ab8500-rtc", rtc);
 496        if (err < 0)
 497                return err;
 498
 499        platform_set_drvdata(pdev, rtc);
 500
 501        err = ab8500_sysfs_rtc_register(&pdev->dev);
 502        if (err) {
 503                dev_err(&pdev->dev, "sysfs RTC failed to register\n");
 504                return err;
 505        }
 506
 507        return 0;
 508}
 509
 510static int ab8500_rtc_remove(struct platform_device *pdev)
 511{
 512        ab8500_sysfs_rtc_unregister(&pdev->dev);
 513
 514        return 0;
 515}
 516
 517static struct platform_driver ab8500_rtc_driver = {
 518        .driver = {
 519                .name = "ab8500-rtc",
 520                .owner = THIS_MODULE,
 521        },
 522        .probe  = ab8500_rtc_probe,
 523        .remove = ab8500_rtc_remove,
 524        .id_table = ab85xx_rtc_ids,
 525};
 526
 527module_platform_driver(ab8500_rtc_driver);
 528
 529MODULE_AUTHOR("Virupax Sadashivpetimath <virupax.sadashivpetimath@stericsson.com>");
 530MODULE_DESCRIPTION("AB8500 RTC Driver");
 531MODULE_LICENSE("GPL v2");
 532
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